• 한국가시화정보학회지
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• 제21권3호
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• pp.57-64
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• 2023

An open pulsating heat pipe operates continuously by inflow and outflow fluids through an open-type condenser. The open pulsating heat pipe is a device capable of obtaining the thrust due to the variation of internal pressure during phase change. Therefore, the open pulsating heat pipe is a suitable device to move fluids if the heat source such as waste heat exists. Many numerical studies have not been sufficiently conducted on the open pulsating heat pipe. In this study, the numerical analysis of the open pulsating heat pipe is performed according to the length of the condenser section. The OpenFOAM software is used to obtain the thrust and the flow visualization for the open pulsating heat pipe.

• Journal of Mechanical Science and Technology
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• 제17권3호
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• pp.422-428
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• 2003

This study concerns the performance of the heat transfer of the thermosyphons having 60, 70, 80. 90 axial internal low-fins in which boiling and condensation occurr. Water, HCFC-141b and CFC-11 have been used as the working fluids. The operating temperature, the liquid charge ratio and the inclination angle of thermosyphons have been used as the experimental parameters. The heat flux and heat transfer coefficient at the condenser are estimated from experimental results. The experimental results have been assessed and compared with existing theories. As a result of the experimental investigation, it was found that the maximum heat flow rate in the thermosyphons is dependent upon the liquid charge ratio and inclination angle. A relatively high rate of heat transfer has been achieved by the thermosyphon with axial internal low-fins. The inclination of a thermosyphon has a notable influence on the condensation. In addition, the overall heat transfer coefficients and the characteristics at the operating temperature are obtained for the practical applications.

• Geomechanics and Engineering
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• 제20권4호
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• pp.299-312
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• 2020

The aim of this paper was to investigating the effects of soil relative density, construction materials roughness, oil type (gasoil, crude oil, and used motor oil), and oil content on the internal and interface shear behavior of sand with different construction materials by means of a modified large direct shear test apparatus. Tests conducted on the soil-soil (S-S), soil-rough concrete (S-RC), soil-smooth concrete (S-SC), and soil-steel (S-ST) interfaces and results showed that the shear strength of S-S interface is always higher than the soil-material interfaces. Internal and interface friction angles of sand beds increased by increase in relative density and decreased by increasing oil content. The oil properties (especially viscosity) played a major role in interface friction behavior. Despite the friction angles of contaminated sands with viscous fluids drastically decreased, it compensated by the apparent cohesion and adhesion developed between the soil grains and construction materials.

• 한국전산유체공학회:학술대회논문집
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• 한국전산유체공학회 2010년 춘계학술대회논문집
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• pp.496-500
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• 2010

Understanding train-wind is the best method to know how to optimize subway ventilation system. The capacity and efficiency of the subway ventilation system are known by pressure and velocity while train runs. Analysis of the internal flow in subway tunnel and around subway station are studied using numerical methods. Characteristics of internal flow and influence of subway ventilation system for the subway station with platform screen door and tunnel are analyzed by unsteady state analysis. Velocity and pressure of train wind transformation are compared at around subway ventilation system and the internal flow is investigated at the subway tunnel.

• Tuberculosis and Respiratory Diseases
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• 제49권5호
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• pp.568-575
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• 2000

연구배경 : Cytokine은 주요한 염증 매개 물질로서 질환에 따라 다른 양상을 보일 수 있어, 흉수를 일으키는 다양한 원인 질환의 감별에 이용되어 왔다. 이 중에서 악성 흉수, 결핵성 흉수, 부폐렴 삼출액 및 농흉에서 INF-${\gamma}$, IL-2R, IL-6, IL-1를 동사에 측정하여 비교한 연구는 많지 않아 본 연구를 시행하게 되었다. 방법 : 흉수를 주소로 내원한 환자 중에서 흉수 천자로 삼출액이 확인된 환자들을 대상으로 흉수를 채취하여, ELISA kit를 이용하여 INF-${\gamma}$, IL-2R, IL-6, IL-10 농도를 측정하였다. 결과 : 악성 흉수, 결핵성 흉수, 부폐렴 삼출액 및 농흉에서 흉수 내의 cytokine의 순서대로, INF-${\gamma}$는 $16.7{\pm}50$, $295.5{\pm}585.5$, $10.0{\pm}0$ pg/ml, IL-2R은 $3247.4{\pm}1713.3$, $7423.5{\pm}3752.8$, $3790.2{\pm}3201.1$ pg/ml, IL-6는 $600{\pm}12.8$, $556.4{\pm}161.7$, $514.4{\pm}224.8$ pg/ml, IL-10은 $28.2{\pm}55.5$, $11.3{\pm}11.7$, $98.4{\pm}141.7$ pg/ml로 각각 측정되어, 결핵성 흉수가 다른 원인의 흉수에 비해 IL-2R 농도가 의 있게 높았으며, IFN-${\gamma}$ 농도도 높은 경향을 나타내었으며, 부폐렴 삼출액에서는 IL-10농도가 다른 원인의 흉수에 비해 의미있게 높았다. 결론 : 결론적으로 흉수 내의 IL-2R농도 측정은 결핵성 흉수와 다른 원인의 흉수를 감별하는데 어느 정도 도움이 될 것으로 사료되며, IL-10 측정은 부폐렴 삼출액과 다른 원인의 흉수를 감별하는데 어느 정도 도움을 줄 것으로 생각된다.

• Tuberculosis and Respiratory Diseases
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• 제61권3호
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• pp.256-264
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• 2006

연구배경: 급성폐손상에서 염증세포의 모집과 활성, 그 염증세포의 부산물인 활성산소, 사이토카인, 기질단백분해효소등과 기획성 세포사멸이 폐실질 파괴와 재구성에 중요한 역할을 하는 것으로 알려져 있다. 또한 당뇨환자에서 세균 감염 시 중성구의 기능 이상과 활성 산화기의 기능이상, 살균 능의 저하를 가져온다고 알려져 있으나 단백분해효소 대한 견해가 부족한 편이다. 본 연구에서는 동물 모델에서 내독소로 유발된 급성폐손상의 기전에 중요한 역할을 하는 단백분해효소와 그 억제제의 분비를 비교 관찰하였다. 방 법: 생후 6주된 수컷 쥐 40마리를 정상군, 당뇨군, 내독소군, 당뇨-내독소군으로 나누어 당뇨군은 streptozotocin을 투여하였고 내독소군은 지질다당질을 투여하고서 희생시켰다. 각각 혈액, 기관지폐포세척액을 얻어 gelatin zymography를 이용하여 MMP-9의 활성을 측정하였고 Western blot으로 TIMP-1을 측정하였다. 결 과: 1) 내독소군과 당뇨-내독소군은 정상과 당뇨군에 비해 폐 무게의 증가와 기관지폐포세척액과 폐 조직 소견상 염증세포, 특히 중성구의 증가를 보였고 기관지폐포세척액 내 단백질 양의 증가를 보였다 (p < 0.05). 또한 당뇨-내독소군은 내독소군과 달리 기관지폐포세척액 내 총 염증세포 수가 유의하게 감소하였다 (p = 0.001). 2) MMP-9의 활성은 혈청에서는 당뇨-내독소군이 다른 세 군보다 가장 높은 활성을 보였고 기관지폐포세척액에서는 내독소군과 당뇨-내독소군은 차이가 없었으나 정상과 당뇨군에 비해 높은 활성을 보였다 (p < 0.05). TIMP-1 발현은 혈청에서는 네 군간의 차이가 없었고 기관지폐포세척액은 당뇨-내독소군이 가장 낮은 발현을 보였다 (p < 0.05). MMP-9/ TIMP-1 density ratio를 비교했을 때 기관지폐포세척액에서 당뇨-내독소군이 다른 세 군보다 높았고 내독소군도 정상과 당뇨군보다 높았다 (p < 0.05). 결 론: 급성폐손상이 있는 당뇨에서는 염증세포의 화학 주성 감소로 중증 감염에 민감해지고, 기질단백분해효소 활성 증가와 그 억제제의 감소로 폐손상이 가중될 것으로 예상된다.

• 한국유체기계학회 논문집
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• 제11권2호
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• pp.13-19
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• 2008

Butterfly valves are widely used as control valves for industrial process. For the definition of optimum configuration of the valve, wide range of related studies has been actively conducted in the case of working fluids of water or air under the normal temperature. Recently, internal flow and performance characteristics of cryogenic butterfly valve for LNG carrier take a growing interest in the field of research and development. Therefore, present study is aimed to investigate the internal flow and performance characteristics of the cryogenic butterfly valve because the study result for the valve can be hardly found at present. Part 1 of this paper describes the study result of a butterfly valve model under the condition of the normal temperature. Succeeding Part 2 of this paper will describe the internal flow characteristics of a cryogenic butterfly valve for LNG carrier. The results of Part 1 show that pressure loss coefficients and flow rate coefficients obtained by the present experiment and CFD analysis agree well each other. Moreover, internal flow visualization for the valve by CFD analysis and PIV measurement have revealed complicated flow patterns of the internal flow field in detail.

• Tuberculosis and Respiratory Diseases
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• 제42권4호
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• pp.447-454
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• 1995

Cytokine release from alveolar macrophages and subsequent interaction of these cytokines with the bronchial epithelium can induce epithelial cells to release inflammatory mediators. Nitric oxide(NO), a highly reactive gas formed from arginine by nitric oxide synthase(NOS), is known to be involved in inflammation and edema formation, and the inducible form of NOS(iNOS) can be increased by cytokines. In this context, we hypothesized that lung epithelial cells could be stimulated by cytokines released by alveolar macrophages to express iNOS. To test this hypothesis, the murine lung epithelial cell line, LA-4, or the human lung epithelial cell line, A549, were stimulated with culture supernatant fluids from alveolar macrophages. NO production was assessed by evaluating the culture supernatant fluids for nitrite and nitrate, the stable end products of NO. Both murine and human cell culture supernatant fluids demonstrated an increase in nitrite and nitrate which were time- and dose-dependent and attenuated by $TNF{\alpha}$ and IL-$1{\beta}$ antibodies(p<0.05, all comparisons). Consistent with these observations, cytomix a combination of $TNF{\alpha}$, IL-$1{\beta}$, and $\gamma$-interferon, stimulated the lung epithelial cell lines as well as primary cultures of human bronchial epithelial cells to increase their NO production as evidenced by an increase in nitrite and nitrate in their culture supernatant fluids, an increase in the iNOS staining by immunocytochemistry, and an increase in iNOS mRNA by Northern blottin(p<0.05, all comparisons). The cytokine effects on iNOS were all attenuated by dexamethasone. To determine if these in vitro observations are reflected in vivo, exhaled NO was measured and found to be increased in asthmatics not receiving corticosteroids. These data demonstrate that alveolar macrophage derived cytokines increase iNOS expression in lung epithelial cells and that these in vitro observations are mirrored by increased exhaled NO levels in asthmatics. Increased NO in the lung may contribute to edema formation and airway narrowing.

• Tuberculosis and Respiratory Diseases
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• 제59권3호
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• pp.306-310
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• 2005

저자들은 결핵성 뇌수막염을 가진 31세 남자환자에서 심한 다뇨와 저나트륨혈증, 저혈압, 요중 염분소실이 동반되어 있어 CSWS로 진단하고 항결핵제 투여와 식염수, 염류코르티코이드의 투여 후 임상적 호전을 보인 증례 1예를 경험하였기에 보고하는 바이다.

• BMB Reports
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• 제52권7호
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• pp.463-468
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• 2019

Autosomal dominant polycystic kidney disease (ADPKD), one of the most common human monogenic diseases (frequency of 1/1000-1/400), is characterized by numerous fluid-filled renal cysts (RCs). Inactivation of the PKD1 or PKD2 gene by germline and somatic mutations is necessary for cyst formation in ADPKD. To mechanistically understand cyst formation and growth, we isolated RCs from Korean patients with ADPKD and immortalized them with human telomerase reverse transcriptase (hTERT). Three hTERT-immortalized RC cell lines were characterized as proximal epithelial cells with germline and somatic PKD1 mutations. Thus, we first established hTERT-immortalized proximal cyst cells with somatic PKD1 mutations. Through transcriptome sequencing and Gene Ontology (GO) analysis, we found that upregulated genes were related to cell division and that downregulated genes were related to cell differentiation. We wondered whether the upregulated gene for the chemokine CXCL12 is related to the mTOR signaling pathway in cyst growth in ADPKD. CXCL12 mRNA expression and secretion were increased in RC cell lines. We then examined CXCL12 levels in RC fluids from patients with ADPKD and found increased CXCL12 levels. The CXCL12 receptor CXC chemokine receptor 4 (CXCR4) was upregulated, and the mTOR signaling pathway, which is downstream of the CXCL12/CXCR4 axis, was activated in ADPKD kidney tissue. To confirm activation of the mTOR signaling pathway by CXCL12 via CXCR4, we treated the RC cell lines with recombinant CXCL12 and the CXCR4 antagonist AMD3100; CXCL12 induced the mTOR signaling pathway, but the CXCR4 antagonist AMD3100 blocked the mTOR signaling pathway. Taken together, these results suggest that enhanced CXCL12 in RC fluids activates the mTOR signaling pathway via CXCR4 in ADPKD cyst growth.